The invention is generally directed to toner and developer compositions, and more specifically, the present invention is directed to developer and toner compositions with certain charge enhancing additives or a mixture of charge enhancing additives, which additives impart, or assist in imparting a positive charge to the toner resin particles and enable toners with rapid admix characteristics. In one embodiment, there are provided in accordance with the present invention toner compositions comprised of resin particles, pigment particles, and a nonionic fluorosurfactant charge enhancing additive enabling, for example, rapid admix of less than about 30 seconds, stable admix characteristics, extended developer life, stable electrical properties, and compatibility with fuser rolls including Viton fuser rolls. The aforementioned toner compositions usually contain pigment particles comprised of, for example, carbon black, magnetites, cyan, magenta, yellow, blue, green, red, brown components, or mixtures thereof in an embodiment, thereby providing for the development of black or colored images. Moreover, in an embodiment the nonionic fluorosurfactant charge enhancing additives of the present invention can be added to toners containing charge enhancing additives such as distearyl dimethyl ammonium methyl sulfate wherein, for example, the admix characteristics are improved, for example the aged toner will have an admix of from about 5 to about 60 seconds as determined by a charge spectrograph; and additionally the triboelectric charging values of the aforementioned toner are a desirable 10 to about 40 microcoulombs per gram as determined by the Faraday Cage method for extended time periods. The nonionic fluorosurfactant charge enhancing additives of the present invention allow in embodiments for maintaining the charging and admixing ability of the toner over extended periods of storage and at elevated storage temperatures. Furthermore, the nonionic fluorosurfactant charge enhancing additives in an embodiment of the present invention can be applied to the surface of previously formulated toners for the primary purpose of prolonging the shelf life thereof. In this manner, the charging and admix shelf life of toners can be maintained for up to one year in an embodiment of the present invention. The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics as indicated herein, and maintain their triboelectric charging capability for an extended number of imaging cycles exceeding, for example, 300,000. Also, the toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes including color processes. Moreover, in another embodiment of the present invention the toner compositions thereof can be initially formulated and thereafter subjected to a washing step with a solution containing the nonionic fluorosurfactant additive of the present invention. Furthermore, in another embodiment the nonionic fluorosurface charge enhancing additive can be sorbed or coated on flow aid additive, such as colloidal silica, and the resulting composite can be added to the toner composition, preferably on the surface thereof, in an effective amount thereby enabling a positively charging toner with, for example, stable admix properties for extended time periods in some embodiments of the present invention.
Developer compositions with charge enhancing additives, which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts R.sub.4 N as charge control agents for electrostatic toner compositions. There is also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica.
Also, there are disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can imparat a positive charge to the toner composition. Further, there are disclosed in U.S. Pat. No. 4,298,672 positively charged toner compositions with resin particles and pigment particles, and as charge enhancing additives alkyl pyridinium compounds. Additionally, other documents disclosing positively charged toner compositions with charge control additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,430 and 4,560,635.
Compositions with inner salt charge enhancing additives are illustrated in U.S. Pat. No. 4,752,550, the disclosure of which is totally incorporated herein by reference. It is indicated in column 3, beginning at line 57, that one of the objects of the invention of the '550 patent resides in providing toner compositions containing mixtures of inner salt charge enhancing additives and other known charge enhancing additives. Examples of mixtures of charge enhancing additives are illustrated in column 4, beginning at line 1, and include mixtures of the inner salts with, for example, distearyl dimethyl ammonium methyl sulfate, reference U.S. Pat. No. 4,560,635; organic sulfate and sulfonate compositions inclusive of stearyl phenethyl dimethyl ammonium tosylates, reference U.S. Pat. No. 4,338,390; and alkyl pyridinium chlorides including cetyl pyridinium chloride, reference U.S. Pat. No. 4,298,672. Advantages of the toner and developers of the '550 patent, particularly when they include therein one additive such as the inner salts, see column 9, and note the working Examples, include rapid admix, that is the toner compositions will acquire a positive charge in a period of from about 5 seconds to about 1 minute, see column 9, beginning at line 17; compatibilty with Viton fuser rolls; lower fusing temperatures, that is from about 20.degree. F. to about 40.degree. F., than are achievable for toners and developers having incorporated therein some of the charge enhancing additives of the prior art, including quaternary ammonium salts.
In a patentability search report, there were mentioned as prior art U.S. Pat. No. 4,835,084, the disclosure of which is totally incorporated herein by reference, and 4,851,318. In the '084 patent there is disclosed a toner and method of preparation thereof wherein suspension stabilizer particles are removed from the surface of polymer particles by dissolving these particles in a solution containing a fluoroalkyl polyether surfactive agent, reference the Abstract of the Disclosure, and note the disclosure beginning in column 2, particularly column 2, line 50, wherein it is indicated that the stabilizers present on the surface of polymer particles are removed by the dissolution thereof wherein this dissolution is conducted in the presence of a fluoroalkyl polyether surface active agent, examples of these materials being illustrated in column 3, including Zonyl FSN available from E.I. DuPont Company. The fluorosurfactants of this patent can be selected as the charge enhancing additive of the present invention in embodiments thereof. In the '318 patent, there are described processes for encapsulated toners wherein there are selected polyethylene oxide surfactant protective colloids, which provide a toner composition that is not sensitive to humidity. According to the teachings of this patent, the surfactant can function as a stearic stabilizer to prevent coagulation, see for example column 4 and column 5 of the patent, as well as the working Examples thereof and note the types of specific surfactants that can be selected, see column 6 , for example, beginning at line 45, and the disclosure in column 9.
Moreover, toner compositions with negative charge enhancing additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The '974 patent discloses negatively charged toner compositions comprised of resin particles, pigment particles, and as a charge enhancing additive ortho-halo phenyl carboxylic acids. Similarly, there are disclosed in the '064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing-additives.
There is illustrated in U.S. Pat. No. 4,404,271 a process for developing electrostatic images with a toner which contains a metal complex represented by the formula in column 2, for example, and wherein ME can be chromium, cobalt or iron. Additionally, other patents disclosing various metal containing azo dyestuff structures wherein the metal is chromium or cobalt include U.S. Pat. Nos. 2,891,939; 2,871,233; 2,891,938; 2,933,489; 4,053,462 and 4,314,937. Also, in U.S. Pat. No. 4,433,040, the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions with chromium and cobalt complexes of azo dyes as negative charge enhancing additives.
Other illustrative prior art includes Japanese Publication No. 54-145542 which illustrates a negatively chargeable toner consisting of a resin, a colorant, and the charge control agent pyridoxine aliphatic acid ester; East German Patent Publication 218697 relating to liquid developers with charge control additives with structural units of Formulas (I), (II) and (III), and which contains olefinically polymerizable bonds; U.S. Pat. No. 3,850,642 relating to multilayer sensitive elements with ionizable salts, acids, esters, and surfactants as charge control agents; U.S. Pat. No. 2,970,802 illustrating a composition for the control of hypercholestermia, which composition consists of a nontoxic gelatin containing aluminum nicotinate; and U.S. Pat. No. 3,072,659 which discloses a method of preparing aluminum salts of nicotinic acid.
In U.S. Pat. No. 4,904,762 (D/89059), the disclosure of which is totally incorporated herein by reference, there are illustrated toner compositions comprised of resin, pigment, or mixtures thereof, in some instances dye, a first charge enhancing additive of a quaternary ammonium salt, and preferably distearyl dimethyl ammonium methyl sulfate, reference U.S. Pat. No. 4,560,635, the disclosure of which is totally incorporated herein by reference, and a second charge enhancing additive comprised of an alkyl ammonium bisulfate, wherein alkyl contains from 1 to about 20, and preferably from 1 to about 10 carbon atoms, such as distearyl dimethyl ammonium bisulfate, tetramethyl ammonium bisulfate, tetraethyl ammonium bisulfate, tetrabutyl ammonium bisulfate, and the like. The aforementioned charge additives can be incorporated in effective amounts into the toner or may be present on the toner surface. While not being desired to be limited to theory, it is believed that the first additive functions primarily as the charge control-component, and the second additive functions primarily as the admix charge component. The aforementioned first additive is present in various effective amounts depending on the amounts of the other components, for example. Preferably, the first additive is present in an amount of from about 0.05 to about 3 and more preferably about 0.1 to about 0.5 weight percent. Other effective amounts of first additive may be selected. Specific examples of the second charge enhancing additives selected for the aforementioned toner compositions include alkyl ammonium bisulfates, such as distearyl dimethyl ammonium bisulfate, tetramethyl ammonium bisulfate, or tetraalkyl ammonium bisulfates (HSO.sub.4), reference U.S. Pat. No. 4,937,157 (D/89260), and copending application U.S. Ser. No. 396,497 (D/89261), entitled "Quaternary Ammonium Compounds and Processes Thereof", the disclosures of each of these applications being totally incorporated herein by reference, tetraethyl ammonium bisulfate, tetrabutyl ammonium bisulfate, and the like. The second additive is present in various effective amounts depending on the amounts of the other components, for example. Preferably, the second additive is present in an amount of from about 0.05 to about 2 and more preferably 0.1 to 0.3 weight percent. Other amounts of second additive can be selected, especially if the objectives of rapid admix and appropriate triboelectric characteristics are achieved. The charge additive mixtures can be present in the toner or on the surface thereof. For example, the toner compositions can be prepared by melt mixing resin, pigment, and the first and second charge additive; melt mixing the toner resin, pigment, and the first additive, followed by external blending of the second additive; or melt mixing the toner resin, pigment, and the second additive followed by external blending of the first additive.
Although toners with charge enhancing additives are known, there continues to be a need for toners which possess many of the advantages illustrated herein. Additionally, there is a need for positive charge enhancing-additives which are useful for incorporation into black or colored toner compositions. Moreover, there is a need for color toner applications with fluorosurfactant charge enhancing additives. There is also a need for toner compositions containing certain fluorosurfactant charge enhancing additives, which toners possess acceptable triboelectric charging characteristics, and excellent admixing properties. Moreover, there continues to be a need for humidity insensitive positively charged toner and developer compositions. Further, there is a need for toners with fluorosurfactant charge enhancing additives which can be easily and permanently dispersed into the toner resin particles. There also is a need for positively charged black and colored toner compositions that are useful for incorporation into various imaging processes, inclusive of color xerography, as illustrated in U.S. Pat. No. 4,078,929, the disclosure of which is totally incorporated herein by reference; laser printers; and additionally, the toner compositions of the present invention are useful in imaging apparatuses having incorporated therein layered photoresponsive imaging members, such as the members illustrated in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Furthermore, there is a need for toner compositions whose triboelectric charging characteristics and admixing properties can be adjusted independently. Also, there is a need for toner compositions which possess a triboelectric charge level of from about 10 to about 40 microcoulombs per gram, and preferably from about 10 to about 30 microcoulombs per gram, and admix charging times of from about 5 to 60 seconds, and preferably less than 15 seconds, as determined by a charge spectrograph, especially at low concentrations, for example less than 1 percent, and preferably less than 0.5 percent of the charge enhancing additives in one embodiment and which have stable admix properties for a minimum of at least six months and preferably for greater than one year at temperatures of up to about 120.degree. F. in embodiments thereof.
Also, there is a need for toner compositions wherein the charge enhancing additive is present on the surface of the toner particles or may be present as a composite, for example, with flow aid additives such as colloidal silicas on the surface toner compositions. Another need of the present invention resides in the provision of toner compositions wherein the charge enhancing additive is a nonionic fluorosurfactant which is coated on the surface of the toner particles. Furthermore, another need resides in the formulation of toners with stable admix characteristics for extended time periods, which toner compositions are formulated and subsequently washed with a solution containing a nonionic fluorosurfactant and wherein such surfactants remain on the surface of the toner particles subsequent to washing.